1. Field of the Invention
The invention relates to silicas and silicates obtained and obtainable by acid precipitation of alkali metal silicates at constant alkali number, and to their use, for example as carriers.
2. Discussion of the Background
Precipitated silicas as carrier materials, particularly for vitamin E acetate or choline chloride have long been known. For example, EP 0 937 755 describes how a precipitated silica is prepared by a pH-controlled precipitation reaction and then spray-dried. Precipitated silica prepared in this way is particularly suitable for use for adsorbing liquid active substances such as choline chloride solution or vitamin E, for example. DE 198 60 441 discloses how an active substance adsorbate may be prepared from a precipitated silica and an active substance by spraying or injecting a silica suspension together with one or more active substances into a fluidized bed generated using hot air. It is likewise possible to use hydrophobic precipitated silicas for these purposes, as described in DE 198 25 687.
In the context of their use as carriers, the following properties of silicas are important:
adsorption capacity, good sorption kinetics, and low fine dust fraction. Owing to heightened safety requirements and the need to prepare adsorbates with ever higher concentrations, there is therefore a demand for carrier silicas which have a very low fines fraction with an adsorptiveness which is heightened at the same time.